In the field of oncology it is important to be able to discriminate tumor tissue from normal tissue. Typically, tissue is inspected at a pathology department after a biopsy or after surgical resection. A drawback of this current way of working is that real time feedback during the procedure of taking a biopsy or performing the surgical resection is missing. A way to provide such feedback to a medical device or medical probe, for instance a biopsy needle, is to incorporate optical fibers to perform optical measurements at the tip of the medical probe.
Various optical methods can be employed with diffuse reflectance (DRS) and autofluorescence measurement as the techniques that are most commonly investigated. Several probes can be used to perform these measurements but in general these probes have blunt end surfaces and are therefore difficult to combine as a direct integral part of a single medical probe.
The U.S. Pat. No. 4,566,438 discloses a sharp fiber-optic stylet in which two optical fibers are incorporated that could perform DRS and fluorescence measurements at the tip of the needle. However the optical fibers in the stylet are beveled and as a result a significant part of the light in the optical fiber will undergo total internal reflection at the tip of the needle, reaching the cladding material of the optical fiber and then exiting the optical fiber. This travelling through the buffer can cause a significant amount of unwanted autofluorescence of the cladding material hampering the measurement of the tissue autofluorescence.